This application claims the priority of German application 198 51 923.0, filed in Germany on Nov. 11, 1998, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to an arrangement for transporting yarn through a heat setting chamber having a preferably rotatably driven central mast, which is fitted with a plurality of transport belts arranged in cross section around it in the form of a polygon, the transport belts being driven in transport direction, around which transport belts at least one yarn is wound in ordered loops by means of a winding flyer, which loops have, at the latest at arriving at the heat setting chamber, a larger circumference for the purpose of forming a shrinkage reserve than that of the polygon formed by the transport belts.
An arrangement of this type, also comprising a rotatably driven central mast, is prior art in U.S. Pat. No. 3,683,650. For the purpose of forming the desired shrinkage reserve, it is provided in this arrangement that the outer ends of the transport belts, before they run into the heat setting chamber, are guided step-like nearer up to the mast with the aid of guiding rollers, so that downstream of the guiding rollers in the area of the heat setting chamber, the loops of the yarn can hang freely on the upper ends of the transport belts and thus can shrink freely in the heat setting chamber. This type of formation of a shrinkage reserve loads the transport belts with an increased tension and results in a higher power consumption for the transport belt drive.
It is an object of the present invention to form a shrinkage reserve in an arrangement of the above mentioned type, which reserve is more favorable with regard to the loading of the transport belts and to power consumption.
This object has been achieved in accordance with the present invention in that auxiliary belts, ending upstream of the heat setting chamber, are arranged in the area of the winding flyer, the speed of which auxiliary belts corresponds to the speed of the transport belts, and which enlarge the polygon by the amount of the desired shrinkage reserve.
Due to the features according to the present invention, the transport belts are not additionally loaded for the purpose of forming a shrinkage reserve. While in prior art the polygon, formed by the transport belts, is reduced upstream of the heat setting chamber as a result of being pressed together, in the case of the present invention, a larger polygon is formed with the aid of the auxiliary belts, whereby before the loops of yarn reach the heat setting chamber, they are disposed subsequently on the polygon formed by the transport belts, whereby the desired shrinkage reserve occurs by itself.
The auxiliary belts can have a separate drive, which is adapted to the drive of the transport belts. In an advantageous embodiment of the present invention it is provided that driven guiding rollers are arranged for the transport belts, by means of which the auxiliary belts are also driven. This saves not only a separate drive for the auxiliary belts, but also ensures that the speed of the transport belts and of the auxiliary belts are absolutely identical.
If it is additionally desired that the central mast rotates slightly, the guiding rollers are advantageously arranged at a housing which rotates around the axis of the central mast. This ensures that all areas of the yarn loops take up the same position one after the other and thus are reached in the same way by the heat setting medium located in the heat setting chamber.
A planetary gearing is provided for the rotating drive of the central mast. This does not, as in the case of prior art, consist of engaged toothed wheels, but rather comprises disc wheels having flat belts, by means of which the drive of the planetary gearing is simplified. This design is based on the knowledge that the central mast must in no way rotate in an exactly defined relation to the winding flyer, so no overly high demands are made on the exactness of the rotational drive.